This invention particularly concerns the problem involved by charging a succession of metal plates, normally one at a time, into a metal melt.
As an example of a practice involving this problem, copper cathodes which are relatively thin as compared to their length and width, are charged successively, one after another, to a copper melt contained in a melting crucible which supplies a crucible through which elongated copper products, such as wire, are continuous passed and on which the melt copper is cast, the melting crucible requiring substantially continuous charging of the copper cathodes to maintain its melt volume.
In any event, the top level of any metal melt customarily floats a reactive or protective layer; in the case of a copper melt, the layer may be coke granules floating on the melt. Therefore, it is impractical to charge metal plates one after another, by dropping the plates flatly on top of the layer floating on the melt, particularly when the plates are relative thin, because the plates may not sink through the layer until a number pile one on top of another, this resulting in uneven charging of the melt; in the case of the practice involving copper and referred to above, it is, of course, desirable to continuously and uniformly add copper to the melt as the melt is continuously and uniformly carred away from the melt by the elongated products passed through the melt.
For practical reasons, the melt and the layer floating on the melt are contained in a crucible provided with means for adding heat to the melt as required, the crucible having a roof with a charging opening. Various shapes of crucibles may be used; in the case of the previously described practice, the elongated products may be passed by a specially designed crucible which, however, must be continuously supplied through a suitable conduit by a crucible containing a heated melt and the layer, and requiring continued charging through a charging opening above the melt.
Because of the problem connected with attempts to drop the plates flatly onto the melt and its layer, attempts have been made to drop the plates edgewise, one after another, but for practical reasons, the plates must be delivered to the crucible at a substantial height above the charging opening, this resulting in the plates gravitationally acquiring a relatively high falling velocity and resulting in the melt being splashed about within the crucible. In the case of the practice referred to before, the design of the supply crucible is such that splashing of the copper melt may result in the splashed metal freezing around the charging opening and putting the equipment out of operation.